1. Field of the Invention
This invention relates to rupture discs and a method of manufacturing the same.
2. Description of the Related Art
One type of rupture disc that is known in the prior art is represented by Canadian Patent 674,719. In this patent, it will be seen that the rupture disc consists of two elements, a cap and a seal. The cap is made from metal that has been weakened by a plurality (usually 6) of radial slots extending from a circle of small holes near the top of the dome. The sealing member, which may be made of metal or plastic, seals the slit/slots and holes in the cap. When the pressure is applied to the seal it is transferred to the cap and the stress in the cap material between adjacent holes at the top of the slots or slits increases proportionately to the pressure until a failure occurs between two of them. This initiates complete rupture of the disc assembly. By varying the circle diameter of the holes at the top of the slits/slots, the distance between adjacent holes increases or decreases thus increasing or decreasing the strength of the material between adjacent holes and consequently the pressure at which the disc fails or ruptures. The cap material at the top of the dome within the circle diameter of small holes is not attached securely to any of the segments of the cap and, when the disc ruptures, can break free and flow downstream with the discharge. This loose part is known in the industry as a fragment and the disc is therefore a "fragmenting" type disc which is not desirable.